[Website] Existing policies and strong engagement by nations submitting their contributions ahead of the Paris climate meeting will limit anthropogenic greenhouse gas (GHG) emissions by 2030, but a new climate agreement can encourage further action to limit global temperature rise to 2°C by 2100, according to a new United Nations Environment Programme (UNEP) report.

The INDCs represent GHG emission reductions of 4 to 6 gigatonnes of carbon dioxide equivalent per year (GtCO2e/yr) in 2030 compared to projected emissions under current policy trajectories. 2030 projections based on current policies are themselves 5 GtCO2e per year lower than the estimate of 65 GtCO2e, based on the Intergovernmental Panel on Climate Change’s Fifth Assessment Report scenarios, which assumed no additional climate policies are put in place after 2010.

This indicates that efforts to tackle climate change, including those taken before the Paris agreement and full implementation of the INDCs, could cut up to 11 GtCO2e from projected emissions in 2030. This is however around half of the total required to reach the global emission level of 42 GtCO2e in 2030 consistent with having a likely chance (>66 percent) of staying below the 2°C target in 2100.

The challenge is to bend the emissions trajectory down as soon as possible to ensure that the net zero emissions goal in 2060-2075 is within reach…

The report also recommends early action on climate to keep costs as low as possible and avoid deeper and more challenging cuts later.

With regard to the various potential scenarios for the emissions gap in 2025 and 2030, the report finds the following:

The global emission levels consistent with a chance of staying below the 2°C limit, following a least-cost pathway from 2020, 48 GtCO2e (range 46 to 50) in 2025 and 42 GtCO2e (range: 31 to 44) in 2030.

Emissions are projected to be 54 GtCO2e (range 53 to 58) in 2025 and 56 GtCO2e (range 54 to 59) in 2030, if all unconditional INDCs are implemented. This gives emission gaps of 7 GtCO2e (range 5 to 10) and 14 GtCO2e (range 12 to 17) in 2025 and 2030 respectively.

If conditional INDCs are included, the global emissions projection is 53 GtCO2e (range 52 to 56) in 2025 and 54 GtCO2e (range 52 to 57) in 2030. This would give emission gaps of 5 GtCO2e (range 4 to 8) and 12 GtCO2e (range 10 to 15) in 2025 and 2030 respectively.

If countries that have not yet submitted an INDC were to reduce their emissions at the same percentage as those that have already submitted, the gap would narrow by a further 0.5 GtCO2e in 2025 and 1 GtCO2e in 2030…